Sprint versus endurance training: Metabolic adaptations in working human skeletal muscle

BACKGROUND: Brief, intense exercise training induces metabolic adaptations in working human skeletal muscle that are comparable to traditional endurance training (Burgomaster, J Appl Physiol 100 : –2047, 2006). However, no study has directly compared the metabolic adaptations to these diverse training strategies in a standardized manner. PURPOSE: We examined changes in skeletal muscle metabolism during a fixed bout of exercise (1 h cycling at 65% of pre‐training VO2peak) before and after 6 wks of either low volume sprint‐interval training (SIT) or high volume endurance training (ET). Twenty subjects (23±1 yr, VO 2 peak = 41±1 ml/kg/min) were assigned in a counterbalanced manner to a SIT or ET group (n=5 men and 5 women per group). Subjects performed either SIT (4–6 repeats of 30 s “all out” cycling at ~250% VO2peak with 4.5 min recovery per d, 3 d/wk) or ET (40–60 min of continuous cycling at ~65% VO2peak per d, 5 d/wk). Weekly training time commitment was ~1 h for SIT and ~4.5 h for ET, and total training volume was ~80% lower for SIT versus ET (~630 vs ~3000 kJ per wk). Training increased VO2peak and the maximal activity of citrate synthase and 3‐hydroxyacyl‐CoA dehydrogenase with no difference between groups (main effects, P<0.05). Similarly, training decreased net muscle glycogenolysis, phosphocreatine degradation and lactate accumulation but there was no difference between groups (main effects, P<0.05). CONCLUSION: Given the large difference in training volume, these data demonstrate that SIT is a time efficient strategy to induce skeletal muscle metabolic adaptations during exercise that are comparable to ET in young men and women. Supported by NSERC Canada and an ACSM Doctoral Research Grant (KAB)